index (publishing)

An index is a list of words and associated pointers to where those words can be found in a document. In a traditional back-of-the-book index the words (or phrases) are concepts selected by a person and the pointers are page numbers. In a library catalog the words are authors, titles, subject headings, etc., and the pointers are call numbers. Internet search engines, such as Google, are indexes too. The words are words found in HTML (or other documents), and the pointers are URL's.
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